Unbelievable Canadas LARGEST ABANDONED Mega Mansion That's Crazy! In this video we are taking a look at one of the world’s largest abandoned mansions. It currently stands as Canada’s largest mansion at 65,000 square feet and also happens to be completely left to the elements. These guys are taking a look at what’s left after a devastating financial crash from its former owner and also thoughtfully analyzing the true cost of this staggering, huge home. Last listed for sale at $25 million, there is nothing on the planet like this ultra modern, abandoned mansion.